Yume is the student of Kazemi affiliated junior high class 2-1. She is Otome's younger sister, and one of Jun'ichi and Nemu's granddaughters. Her first name literally means "dream." Due to her magician blood, she sees the future in her dreams.

In the first season, Yume's accommodating personality is being portrayed when she easily became friends with Minatsu. Yume is also there to support Minatsu in times of trouble and also show signs of defensiveness towards Minatsu when others found out about the latter being a robot.

In the second season of the anime, Yume is depicted to be rather lonely after Minatsu leaves the school. However, she puts on an independent front when in front of others, especially around Yoshiyuki.

Yume is also shown to harbor romantic feelings for Yoshiyuki and is shown on a few occasions to convey her feelings indirectly by asking Yoshiyuki out. However, Yoshiyuki does not seem to know about it.

When Yoshiyuki first came to stay at the Asakuras' place when he was young, the younger Yume is shown to be very open in her feelings and immediately grab Yoshiyuki's hands to introduce herself.